Showing papers by "University of Copenhagen published in 1975"

A model for estimating actual evapotranspiration from potential evapotranspiration

Abstract: A model for calculating the daily actual evapotranspiration based on the potential one is presented. The potential evapotranspiration is reduced according to vegetation density, water content in the root zone, and the rainfall distribution. The model is tested by comparing measured (EA m ) and calculated (EA c ) evapotranspirations from barley, fodder sugar beets, and grass over a four year period. The measured and calculated values agree within 10 %. The model also yields information on soil water content and runoff from the root zone.

Biomass, net production and growth dynamics in an eelgrass (Zostera marina L.) population in Vellerup Vig, Denmark

Abstract: The biomass of an eelgrass population in Vellerup Vig, Denmark showed a unimodal seasonal pattern, March to October 1974, with the peak in August. Biomass of leaves and flowering turions was quadrupled, biomass of rhizomes doubled from March to August. The maximum total biomass was 443 g dry wt/m2. The leaf production was determined by a leaf marking technique, which also made it possible to estimate the rhizome production. In the period 9 April to 16 October 1974, the leaf production was 856 g dry wt/m2 and the rhizome production 241 g dry wt/m2 , which made a total of 1097 g dry wt/m2. The dominance of leaf production, though leaf and rhizome biomass were of the same magnitude, arose from a higher turnover rate of leaves (1.8 % per day) than of rhizomes (0.7 % per day). On the average a new leaf was produced on each turion every 14 days. The lifetime of the leaves was about 56 days. Total radiation and not temperature seemed to control leaf production. The maximum leaf production rate of 7.9 g ...

Trace Fossils at Omission Surfaces

Abstract: Trace fossils at discontinuity surfaces may be classified as three distinct ’ assemblages, according to their time relationship with the depositional hiatus. These assemblages may be called the “preomission,” “omission “and “postomission” suites. Discrimination of these suites is essential for the stratinomic interpretation of the discontinuity surface. The three suites may represent the same ichnocoenose in different modes of preservation, or the appearance of a new ichnocoenose may suggest the environmental conditions responsible for the omission of sediments and the resumption of deposition.

Induction processes in blood-brain transfer of ketone bodies during starvation

Abstract: Fed and starved rats were studied on successive days during a 5-day starvation period. The ability of ketone bodies to pass the blood-brain barrier was estimated by single common carotid injections of labeled ketone bodies and water, and results were expressed as the ratio between the normalized activities of tracers in tissue and blood, the brain uptake index (BUI). BUI of D-3-hydroxybutyrate and acetoacetate decreased as their total concentrations increased in the injectate bolus: BUI of D-3-hydroxybutyrate decreased significantly from 8% at 0.2 mM to 3--4% at 20.2 mM in fed rats and from 11.5% at 0.2 mM to 6% at 20.2 mM in starved rats, indicating saturation of the uptake mechanism. The BUI of both ketone bodies increased significantly with increasing duration of starvation, indicating adaptation to ketonemia. Enzymatic kinetics explained the uptake behavior of D-3-hydroxybutyrate in both fed and starved rats and involved a rise of Km and Vmax during starvation consistent with a doubling of the transport rate at the degree of ketonemia found in starved rats. The uptake of glucose was not influenced by starvation or ketonemia.

Visual transformation of size.

Abstract: To investigate human visual identification of different-sized objects as identically shaped, matching reaction times were measured for pairs of simultaneously presented random figures. In three experiments, reaction time for correct reactions to test pairs of figures of the same shape and orientation consistently increased approximately linearly as a function of the linear size ratio of the figures. In the second experiment, where this ratio was defined for control pairs as well as for test pairs, reaction time for correct reactions to control pairs showed a similar increase as a function of size ratio. The results suggest that the task was performed by a gradual process of mental size transformation of one of the members of each pair of figures to the format of the other one. Language: en

Climatic changes, Norsemen and modern man

Abstract: Oxygen isotope analysis of anew ice core from the crest of the Greenland ice sheet reveals a climatic record of the past 1,420 years. Climatic changes of medium frequencies are in phase with corresponding changes in Iceland and England, whilst long-term changes at mid Atlantic longitudes are out of phase with Europe and North America. Reconciliation with Norse history suggests a strong climatic impact, and a parallel is drawn to the present critical situation of the human society.

Purine nucleoside phosphorylase from Escherichia coli and Salmonella typhimurium. Purification and some properties.

Abstract: The purine nucleoside phosphorylases from Escherichia coli and from Salmonella typhimurium have been purified to electrophoretic homogeneity and crystallized. Comparative studies revealed that the two enzymes are very much alike. They obey simple Michaelis-Menten kinetics for their substrates with the exception of phosphate for which they show negative cooperativity. Gel filtration on Sephadex G-200 of the native enzymes revealed a molecular weight for both enzymes of 138000 ± 10%. By use of dodecylsulphate gel electrophoresis a subunit molecular weight of 23700 ± 5% was determined, suggesting that both enzymes consist of six subunits of equal molecular weight. When the subunits were partially crosslinked with dimethyl suberimidate before dodecylsulphate electrophoresis six protein bands were observed in agreement with the proposed oligomeric state of the enzyme, consisting of six subunits of equal molecular weight. Analysis of the amino acid composition also indicates that the subunits are identical. 6 M guanidinium chloride dissociates the enzymes; association experiments with native and succinylated enzymes suggested that only the hexameric form is active. Both enzymes could be dissociated into subunits by p-chloromercuribenzoate; this dissociation is prevented by the substrates: the nucleosides, the pentose 1-phosphates, and mixtures of phosphate and purine bases.

Demonstration of Enolase Activity Connected to the Brain‐Specific Protein 14‐3‐2

Abstract: An enzyme activity, enolase (2-phospho-D-glycerate hydro-lyase, E.C. 4.2.1.11), was shown to be connected to the brain-specific protein 14.3.2. Specific staining methods were used on immuno precipitates of the protein. The enzyme activity was strongly inhibited by the addition of fluoride in the presence of phosphate. Metal ion binding capacity of the protein was shown by means of an auto radiographic method.

Absence of Arms in the Axoneme of Immobile Human Spermatozoa

Abstract: The spermiograms of an infertile man were unique in showing normal parameters except for the presence of total immotility in 100 per cent of the spermatozoa. In 100 per Cent of the axonemes of such spermatozoa there was a consistent lack of arms on the doublets of the axoneme. The same feature was found in all stages of spermatid formation. Other less consistent abnormalities were the occasional appearance of extra coarse fibers and axonemal microtubules, and an abnormal relationship between the longitudinal columns of the fibrous sheath and the doublets of the axoneme. All other ultrastructural details compared well with normal spermatozoa. Detailed descriptions of the substructural organization of axonemes from a wide variety of sources have to some extent helped to clarify our understanding of ciliary and flagellar motility. However, at the present time significant information at the molecular level is needed before a functional model comparable to the one known for muscle contraction can be achieved. The presence of a rather unique axonemal defect in the spermatozoa of a sterile man may help to throw some light on these problems. In this report the history of such a patient and the ultrastructural findings in his spermatozoa will be described.

Local muscle blood flow and sustained contractions of human arm and back muscles.

Abstract: The endurance during sustained contraction of elbow, flexors, elbow extensors, and back extensors was tested in 3 human subjects. The force level used was varied between ca. 15 and ca. 75% of maximal isometric strength (IS). The clearance of133Xe from contracting muscles was registered during and after the endurance test. In this way it was possible to determine whether muscle blood flow (MBF) was increased or had stopped during the contraction. Experiments with artificial ischaemia of the upper arm together with MBF measurements showed that MBF was of no importance for continuing sustained contractions above a certain force level, which was 50, 25, and 40% of IS for elbow flexors, elbow extensors and back extensors, respectively. However, the level where longer lasting (>15 min) sustained contraction is possible is directly related to MBF. These levels were 22, 15, and 20% IS for elbow flexors, elbow extensors, and back extensors, respectively.

Mortality and life-table in Down's syndrome.

Abstract: Oster, J., Mikkelsen, M. and Nielsen, A. (Department of Paediatrics, Randers Centralsygehus, Randers, John F. Kennedy Institute, Glostrup, and the Institute for Human Genetics, University of Copenhagen, Denmark). Mortality and life-table in Down's syndrome. Acta Paediatr Scand, 64:322, 1975.–The causes of death in 130 patients with Down's Syndrome and mortality rates from a material of 524 patients were tabulated; a life-table for the ages over 5 years was constructed. An overall death rate of 5–7 times the general population rate was found. No sex difference was observed. The excess mortality was especially high for heart disease and respiratory disease. Also infectious diseases, others than pneumonia and tuberculosis, showed high mortality rates.

Demonstration of terminalis, olfactory, trigeminal and perivascular nerves in the rat nasal septum.

Abstract: The innervation of the nasal septum and around the olfactory bulb has been investigated in rats by means of whole-mount preparations and histological sections Silver staining, OsO4 staining, PAS staining, cholinesterase reaction and fluorescence for catecholamine-containing nerves were used The nervus terminalis forms on the medial side of the olfactory bulb a ganglionated plexus, from which branches are given off which course peripherally with the vomeronasal nerves From a dorsal part of the terminalis nerve plexus an anterior branch is given off which runs along the anterior ethmoidal nerve to the nasal vestibule where it connects with a group of ganglia The peripheral branches of the nerve run from here along two epithelial cristae formed histologically like dermal papillae Ventrally in the respiratory region at the junction of the nasal cavity and the nasopharynx is a 1 times 2 mm area with olfactory epithelium, glands of Bowman and an independent innervation from the olfactory bulb This is the so-called septal olfactory organ Trigeminal nerves form a plexus in the respiratory region and in the vestibule, but do not supply the olfactory region Catecholamine-containing and cholinesterase-positive nerves run along the meningeal arteries on the cribriform plate and accompany their branches to the vascular plexus in the olfactory and respiratory regions Double innervation is found not only of this vascular plexus but of the venous sinuses in the swell bodies of the vestibule The glands of the nose are not surrounded by catecholamine-containing nerves

First-pass metabolism of imipramine in man.

Abstract: The systemic availability of orally administered imipramine (IP) varied from 29 to 77% in 4 subjects. The decrease in availability was due to an excess in metabolism after oral administration. This first%pass metabolism did not correlate with plasma half%life, apparent clearance, or the rate of metabolite excretion in urine. There was close correlation with the excess in formation of demethylated metabolites after oral administration, which suggests that the first%pass metabolism is mediated by demethylation, but does not correlate to the total rate of demethylation.

Determination of brain-specific antigens in short term cultivated rat astroglial cells and in rat synaptosomes.

Abstract: —The brain-specific antigens 14·3·2, GFA, A5, F3, D1, D2, D3 and C1 were quantitated in a short-term astroglial cell culture taken as a model of glial cells, and in synaptosomes, synaptosomal membranes and synaptic vesicles as neuronal material. Furthermore, the antigens were quantitated in newborn rat brain, as this served as the starting material for the cell culture. The membrane antigens C1, D1, D2 and D3 were absent from the cultured astroglia, indicating a neuronal origin for these antigens. C1 was enriched 3-fold in synaptosomes and synaptosomal membranes and more than 10-fold in synaptic vesicles indicating that this antigen might be a marker protein for nerve endings. The name Synaptin is introduced for this antigen. Conversely, the data on the antigens D1, D2 and D3 indicated that these antigens were not restricted to the synaptosomes although they were of neuronal origin. Trace amounts of the cathodal part of the heterogeneous cytoplasmic antigen 14·3·2 were present in the cell culture, possibly originating from a few contaminating neurons. The cytoplasmic antigens A5 and F3 were found both in the astroglial culture and in the synaptosomal fraction. F3, however, was found in low concentration in the synaptosomes and 3-fold enriched in newborn rat brain compared to rat brain from 35-day-old rats or to 21-day-old brain cell cultures. It was therefore regarded as a brain specific fetal antigen. The antigen GFA was highly enriched in the astroglial culture compared to whole brain and only trace amounts were found in the synaptosomal fraction supporting the astroglial origin of this antigen.

Complex tight junctions of epithelial and of endothelial cells in early foetal brain.

Abstract: ?The morphology of epithelial and of endothelial intercellular junctions in human foetal (9-15 weeks gestation) and sheep foetal (50, 60 and 125 days gestation, term 147 days) brain has been studied using the freeze-fracture technique and thin section transmission electronmicroscopy. Freeze-fracture replicas of the choroid plexus of both early human and sheep foetuses showed that the choroidal ependymal cells are linked at the ventricular surface by tight junctions. Freeze-fracture replicas of foetal cortical endothelial cell junctions showed that they are still more complex than those of choroidal epithelial cells, in all specimens so far examined. In some 60 day sheep foetuses the dye Alcian blue, which binds to plasma albumin and which iselectrondense when treated with osmium tetroxide, was injected intravenously a few minutes prior to fixation. The dye penetrated from blood into brain extracellular space and c.s.f. but apparently not by an intercellular route. The dye was found in a tubular system (endoplasmic reticulum) in both choroidal epithelial and cortical endothelial cells. The possibility that protein penetrates into the foetal brain and c.s.f. by a transcellular route is discussed. The possible significance of these findings in relation to previous ideas and studies of the development of blood-brain barrier mechanisms is also considered.

Detection of Biospecific Interaction during the First Dimension Electrophoresis in Crossed Immunoelectrophoresis

Abstract: Lectins were included in the first dimension gel in crossed immunoelectrophoresis of human serum proteins. Con A resulted in a retardation of most glycoproteins during the first electrophoresis and heterogeneous forms of individual glycoproteins could be detected. Ulex europeus lectin gave most of the proteins a higher migration velocity. Pokeweed mitogen did not interact with serum glycoproteins, but it did with serum lipoproteins. The method allows a close study of interacting components, determination of binding specificities, and detection of minor interacting components, including heterogeneous molecular forms.

The synaptonemal complex and the spindle plaque during meiosis in yeast.

Abstract: Meiosis in Saccharomyces cerevisiae proceeds principally in the same manner as in other Ascomycetes. Leptotene is characterized by unpaired lateral components and pachytene by the presence of extensive synaptonemal complexes. The synaptonemal complex has the same dimensions and is similar in structure to those described for other organisms. Chromosome counts can now be made by reconstructing the synaptonemal complexes. Diplotene nuclei consistently contain a single polycomplex. The behaviour, doubling and the fine structure of the spindle plaque provide additional markers for the different stages of meiosis.

Enhanced vesicular transport of exogenous peroxidase across cerebral vessels, induced by serotonin.

Abstract: Previous studies have revealed that the endothelial cells of cerebral vessels are linked by tight junctions preventing an intercellular passage of exogenous peroxidase. However, under normal conditions, vesicular transport of the tracer has been demonstrated in parts of cerebral vessels, especially in arterioles with a diamater of 30–100μ. Solutions, containing 50–800 μg of buffered 5-hydroxytryptamine sulphate (serotonin), were perfused through the cerebral ventricles on mice after intravenous injection of horseradish peroxidase. Usually, the biogenic amine enhanced the vesicular transport of exogenous peroxidase. The serotonin-induced increased transport was observed in vessels on the surface of the brain as well as in vessels located in the parenchyma. No cell damage was observed. Increased transport was observed in arterioles, venules, and in capillaries. Therefore, it is not likely that the serotonin effect in a constriction of smooth muscle cells causing an opening of the tight junctions followed by an intercellular movement of tracer. The most reasonable assumption behind the mechanism is that serotonin affects the plasmamembrane of endothelial cells resulting in an enhanced production and transfer of cytoplasmic vesicles.

Spontaneous alternation in rats with lesions in the frontal lobes: An extension of the frontal lobe syndrome

Abstract: Bilateral lesions in the anteromedial neocortex or the associated part of the neostriatum abolished spontaneous alternation in rats; removal of the suprarhinal strip did not. The classical deficit of spatial choice following frontal-lobe injury is not an artifact of the learning paradigm, but can be extended to unconditioned behavior. Furthermore, the impairment is not restricted to food-reinforced or massed responses. The response-guiding role of the frontal lobe is of such wide generality in the laboratory that it can be expected to operate in the animal’s usual environment as well.

Segmental fibre breakdown and defects of the plasmalemma in diseased human muscles.

Abstract: Thick round fibres common in cross sections of muscle biopsies from patients with muscular dystrophy are due to contracted and swollen segments of otherwise normal muscle fibres. This contracture leads to segmental fibre breakdown, which is identical with Zenker's waxy degeneration. In biopsies from 90 patients suspected of neuromuscular disease, segmental contracture was seen in all or nearly all patients with infantile muscular dystrophy, necrotic myopathy or acute alcoholic myopathy. It was present in half of the patients with polymyositis or myotonic dystrophy. In resticted forms of muscular dystrophy it was rare as it was in neurogenic atrophy. In 9 clinically normal patients it was absent. In electron micrographs of the initial stage sarcomeres were moderately shortened, the sarcoplasmic reticulum was distended and the mitochondria were normal. In the plasmalemma holes were found, through which glycogen granules were lost into the interstitial tissue. In later stages myofibrils were overcontracted and homogenized; in large areas the plasmalemma was absent. Based on these findings a hypothesis for the development of waxy degeneration is proposed: locally defects of the plasmamembrane cause segmental contracture, glycogen granules and water soluble enzymes are lost through holes in the plasma membrane, and finally the affected fibre segment becomes necrotic.

First-pass metabolism of nortriptyline in man.

Abstract: The kinetics of nortriptyline were studied after oral and intravenous (iv) administration of test doses of 50 mg 14C-nortriptyline. The systemic availability of orally administered nortriptyline varied from 0.46 to 0.59 in 6 subjects. The decrease in availability was due to metabolism after administration. Systemic clearance varied from 0.31 to 0.66 L/min. From these measurements indirect estimates of the hepatic blood flow could be made, and a variation from 0.6 to 1.5 L/min was found. Quantitative measurements of first-pass metabolism could also be obtained from urinary metabolite excretion data when the kinetics of metabolite formation and elimination were taken into account. From the second or third day after the test dose, the urinary excretion rate of total radioactivity declined monoexponentially with half-lives closely corresponding to the plasma half-lives of unchanged nortriptyline. Analysis of the data from the iv test according to a 2-compartment open model showed that there was a close correlation between the rate constant of distribution from central to peripheral compartment (k12) and the elimination rate constant in the central compartment (kel). Still, there was some variation in the kel/k12-ratio, and this variation corresponded to the variation of the estimated hepatic blood flow.